For me this is a Booted Warbler. The bill is not long enough and the bird lacks the long sloping forehead of Syke's. The tail is also too short. The plumage has too much contrast with dark tertial centers, alula and primary tips. The dark tip to the lower mandible favours Booted, as does the rather long super, but most significantly there appears to be a thin dark line above the supercilium which Syke's never shows. I always think that Syke's looks structurally like an acrocephalus and Booted more like a phylloscopus and that this bird does not look at all like like an acro.
An excellent record and great photos; well done!
